Lighter Flywheel???

Sorry I can't be of any help just wanted to let you know you're not being ignored just that lightening a KDX flywheel is not a popular mod so info on this will be scarce.

Since light flywheels are used in MX you may want to post this in the CR/KX/RM/YZ forum.

Most professional riders that modify flywheels INCREASE the weight

Well, I had a different bike but the principal is the same.

On my 97 KTM 250 EXC, the flywheel weight was removable. As an experiment I had it removed.

Result - noticeably quicker acceleration but not a huge difference, stalled much more easily in the rock gardens, on roots, whenever the going got really gnarly.

Why? less mass to move made the acceleration quicker, but also made it easier to stop that moving mass, and therefore the engine

Conclusion? I put mine back on.

I wouldn't permanently alter the flywheel unless you can replace it. And I wouldn't do it unless I was going to ride MX or ride trails without much in the way of slow speed obstacles.

If its more snap you're looking for I'd look to your jetting rather than a lighter FFW. CO Dan's assessment is exactly what I would expect to hear and I'm sue you should expect the same results.

I'd suggest playing with new jet needles. If you want more snap look at a C taper needle. They can be had from Sudco, when they are in stock, for about $5. Check out one of the RB Carb mod threads for jetting specs. The starting points quoted there should be very close for you as well. Take note that RB modifies the slide from the factory 5mm cut away to a 7mm cut away.

You can also look at changing gear ratios. Stock the bike uses a 13/47 combo. Give a 12/47 combo a try and see how you like it. If its some thing you want to stick with go to a 13/50 combo when its time to replace your chain and sprockets. The 13/50 combo will require a 110-link chain.

David

owenlo:
Machining the flywheel has been done by at least one poster. 'Fraid I don't recall who, but you can find it with a search. He liked the result.

None of any riding I do would benefit from a lighter weight. That's why I tried a steahly and kept it on!

re: C-taper needles.

How you could use more SPIT in the woods than what you get with such a setup is beyond me. I can turn my bike into a REAL handful with a CEK.....and I doan WANNA handful!! ;)

I run a 12T CS sprocket most of the time. I can change to a 13T anytime I want to in just a minute. Can't do that with a 50T rear (change the ratio quick&easy). If it's something you want to be able to change (depending on where you ride perhaps) at all, keep that in mind.